1. Field of the Invention
The present invention concerns a tape transporting device which transports a recorded tape, on which a signal was recorded earlier, and a blank tape, on which no signal has been recorded, close together for the purpose of duplicating magnetic tapes by a transfer method.
2. Description of the Prior Art
Widespread use of home video recording and playback equipment has increased the demand for prerecorded cassettes, especially half-inch video cassettes. Fast production of such cassettes is difficult, because video signals contain a large amount of information which must be reproduced with a high degree of accuracy to maintain adequate image and color standards.
At present, the preferred video recording method used by this industry is to use upward of 1,000 recording machines, all operating simultaneously, all receiving a realtime signal from one master playback machine to produce multiple copies. The logistics of providing, loading, unloading, operating and maintaining such multitude of relatively complex equipment makes reproduction a very expensive process.
Another approach to magnetic recording duplication is non-realtime duplication known as magnetic replication. In this type of duplication, the signal pattern from a master tape is replicated directly on the receiving tape at very high speed. The magnetic pattern in this process is copied onto a receiving tape in much the same way as a visible image is printed through a high speed press onto a sheet of paper. As a result, the term contact printing has sometimes been used to designate a process of transferring information contained in one recording medium to a second recording medium directly, without an intermediate step of generating an electrical signal. Copy speeds in excess of 100 times realtime duplication have been reported.
A tape replication technique has been developed as a method for duplicating a recorded tape on which a signal was recorded earlier (hereafter referred to on several occasions as a master tape) onto a blank tape on which no signal has been recorded (hereafter referred to on several occasions as a copy tape). When this tape replication technique is implemented, the magnetic medium surface of a master tape is pressed toward the magnetic medium surface of a copy tape, and an external magnetic field or heat is applied to an overlapping area. As a result, a reversed image (i.e., mirror image) of the signal recording pattern recorded on the master tape is formed on the magnetic medium surface of the copy tape, and the duplication is thus completed. If the aforementioned transfer duplication technique is implemented, duplication can be carried out quite efficiently even if video tapes and PCM recording tapes on which complicated signal recording patterns have been impressed are employed, since the transfer is carried out by simultaneously transporting the master tape and copy tape. Numerous conventional duplication devices have been developed.
For example, Japanese Patent Disclosure No. Tokkai Sho 60[1985]-253023. Japanese Utility Model Disclosure No. Jikkai Sho 58[1983]-30937, and Japanese Patent Application Publication No. Kokai Sho 57[1982]-3139 note different formats of duplication devices containing tape transporting devices. A feature common to all these devices is that both a master tape and a copy tape are stretched and transported between a pair of reels (i.e., a feeding reel and a winding reel). The master tape and copy tape are transported simultaneously, and an area in which the master tape is pressed toward the copy tape is established in the middle of the traveling path.
U.S. Pat. No. 4,213,159 notes a tape transporting device wherein the front and rear ends of a master tape are connected to form an endless loop and a copy tape is stretched and transported between a pair of reels (i.e., a feeding reel and a winding reel). In this tape transporting device, too, an area in which the master tape is pressed toward the copy tape is established in the middle of the traveling path.
One of the most important requirements for the aforementioned conventional tape transporting devices is to eliminate positional distortions between the master tape and copy tape in the high-proximity region. Most importantly, if there is a positional error between the master tape and copy tape in the transfer area, the recording pattern of the copy tape is accordingly distorted. When conventional tape transporting devices are employed, the high-proximity area between the master tape and copy tape may be enlarged to eliminate the positional distortion. Attempts have also been made for high-precision control of the tape tension or to physically intimately contact the master tape on the copy tape and drive and transport the overlapping area using a single roller.
In actuality, however, it has been extremely difficult to totally eliminate distortion. Most importantly, there can easily be slippage between the master tape and copy tape, and even if the two tapes are positioned close together by an external force, the tape positions are distorted in response to slight disturbances in the tape transporting device control unit.